Method of precipitating an insoluble sulphide from a. soluble sulphosalt



To all whom it may sca ce am; =Be it known that I, NORMAN a, T.LZU'NITEDZSTATE mach or im une 3H0 Drawing. I M B e filed Jilly 19 a citizen of the United States, and resident of Belleville, infthe county of-fEssex and State of New-Jersey, have invented a new "and useful Improvement in Methods of Precipitating,an'lnsoluble Sulphide from a Soluble Sulphosalt; and I do hereby declare the following to be a full, clear,"and.exact description thereof. v

My invention relates to the formation of chemical precipitates especially insoluble sulphides, and more particularly to that'giderable difliculty.

Ihave discovered that if, instead of "dissolving the sodium sulphantimonate in type of reaction in which two or more soluble chemical com ounds react to form. a third compound w ich is insoluble, or practically so, in the supernatant liquor.

' The object of my invention is toproduce precipitates of such a nature that they can liquor and more easily washed be more easily filtered-from the su ernatant ee from the residual acid or salt than by any'process Zoelow.

heretofore known. It is also my object to produce precipitates which, when dried, may be easily reduced to a powdered state so that. they may perform more satisfactorily their useful functions in the arts.

To these and other ends my process consists in dissolving or disintegrating certain chemical solids especially soluble s'ulphosalts, whether they exist in an anhydrous,

1 amorphous or crystalline state, in an amount of acid or other solution, either concentrated or diluted, which is at least suficient to decompose the solid and produce the desired precipitate, the solid being gradually dissolved and the precipitate being formed as fast as solution takes place.

An essential feature of my invention is that one of the reacting materials is brought into the reaction in solid form, as distinguished from ordinary methods of precipitation .where all of the reacting materials are either originally liquid or are brought into solution before being mixed.

My present invention is the result of investigations directed to improve the prep-' 'aration of antimony pentasulphide, al-

though the principles which I have discovered and which are herein set forth and claimed are by no means confined to producing this substance, several other useful applications of my process being mentioned "FATE Norman in .wztsorr, or 3mm, rmw mnsnr, .assrenon i I or GLEN mzw'mnsny;

NT oFFlcs-..',

r0 DAVID A. srnmr,

i msowsm summon mom: a soriunm L SULrBosALr. a a

1921. {Serial at: 485,922.

entasulphide has been -pre-- is camposed of extremely fine particles, and a which is therefore difiiciilt tofilter and wash.

When dried, the precipitated material is a hard mass. and'can be reduced to the fine powder-required in the arts only with confiltered and washed and, when dried, is friable and easily milled into fine powder. I consider that this remarkable difference betweenmy precipitate and that produced by prior methods is partly due to the rate of solution of the salt in the water present, as well-as upon the increase in the rate of reaction between the'acid and the salt.

I do not wish to be limited to the theory of reaction herein discussed, but it is'my present belief that the novel and surprising results produced by my rocess are largely due to the relatively sm 1 amount of water that is present in contact with the particles of salt when the salt is undergoing reaction. This-is indicated by a comparison of the ordina process of producing antimony pentasu phide by mixing a water solution of sodium sulphant-imona-fe and dilute'suL phuric acid, with the reaction that takes place in my present process. The ordinary method, where the acid and salt are both in solution, proceeds according to the following equation:

water and containing 320 grams of wat'enofcrystalllization, giving a total amou'rit oi grams.

- huric acid uired to-react accordi to P v. ref/q g water"introduoedwitlt t'the salt of 3535' -The'tl1e0retical amount of. sulthe above equation is 588 grams which, with 2055 ns of water gives a solution oi approx mately Be. When the two solut ons vare mixed, the-acid :im-

-"i'nediately'becoines much more dilute, and

.Ivl-o asori' mn 22.25 P y if-no recipitation. takes. place the acid would become:only- 8.63%.;ac1diinstead of, bly this state of affairs comes about momentarily; Iii-the same-manner. the 23% solution of sodium place in a considerably diluted solution.

:In-all probability, because of. this fairly sulphauti-monate is change momentaril to a 14.97%solution. The p'recipitat1on o the antimony V 'pentasulphide, 1 therefore, takes larg e di-lution,,the precipitated, antimony pentasulphide dr'ags water down with it, the

j -flie precipitate water being-1 combined with either as-water of hydration or watercom .lbinedchemically by'hydrelysis'. "This substance, when*dried,*gives up its water and its-particles, like the particles of other well 'lmown'highly hydrated materials,- such as- .the reaction -when solid crystalsof sodium sulphantiinonat are treated with dilute sul- -phuric acid, f o llows thisequation:

a ferric hydroxide and aluminum hydroxide;

- packtogether and form. a cake instead of a a positive direction. That is to say, they all contribute .to produce a precipitate that is In contrast to the reaction discussed,

The sulphantimonate carries with it 'itswater'.oierystallization, but not the 3211 "grams of water required to dissolve it, s in the firstexample. The conditions ofpreoipitation are very-difierent'from those in v the first example. "Probably no reaction other words, {the crystal, after so ution has to. e somewhat-concentrated since. some of sul hantiino'nate.

is, formed-according to my process,

' be flaky ates sultablefor rapid washing an filterbegun, is surrounded b a layer of concentrated sodium sulphant monate solution and this concentrated" solution reacts with the sul huric acid-which,'iin-tu1 n, may-be said its water is-used indissolving the sodiuni ere are several reasons why the precipitate formed in the second'exampie that should and in relatively large ag lomerins- First t e-fi o as? W acid; and this -metho chance to become hydr'ated since theyiare econd, being thus precipitated in locallyconcentrated solution, the articles as formed are in close contact wit each other and they have a chance .to: build up large I precipitated in locally'concentrated solution.

.agglomerates, :this' action being somewhat similar 'to thebuilding up'of largevagglom- "era'tes of ferric hydroxidby digestion n a.

hot solution! Also; sodium sulphates s; formed simultaneously with the precip1tation -of .antimony pentasulphide and in equivalent amounts. Sodium sulphate; as is well known, has a great afiinity; for. water, and this has the double efiect of removing water from the reaction zone, thus makin' the reacting solutions more Yconcentrate and of giv1nga "salting out effect, becauseof its power to take-up the waterwhich' would oth 'rwise tendto hydrate the.- precipitate. y

Also, hen: thereacti n-is completed-the total amount of water p psent w-heuthe sodium'sulp hantimonate is treated .in solid form is less than onehalf the,- water finally present in the ordinaryprocess described in" the example first above iven, ,7 All of these several e cots are additivein,

easily washed and filtered. H

Without limiting my invention to the spe cifioproportions and materials mentioned, the" following "is an example of the preparation of antimony penta'sulphide according to my process.

Prepare 200' Na SbS .9H O' by any of thefwe known methods. Prepare a suiiicient .amount of acid to completely decompose the salt. For this exam 1e, take [grams of concentrated H 0 and dilute toabout 20 B. When the diluted acid has cooled to the desired temperature add the crystals to it and allow it toreact until the evolution of the gas entirely ceases, agitating continuously. Then transfer the material to a suitable-lib ter, wash free from acid, and heat the precipitate in a suitable drier until practically tree from moisture. Q j v The agitation is required toprevent the slowing up of the reaction b the formation ofa layer of reaction pro ucts between the crystals and the acid. The same results are produced by pouring acid upon the solid instead. of introducing the crystals into the is satisfactory when treatin small-amounts ofmateria Home eveigw on my process is carried" ut on a large scale it Is usuall more convenient to introduce the crystals into-the acid.

The precipitate of antimony pentasulhide produced according to my process are but little in appearance from the product of the ordinary ;process where the sograms of. schliplpef s dium sulphantimonate'is dissolved in water before being mixed with acid. My new product is somewhat less gelatinous than the precipitate ofthe ordinary process. and,-

i then in a soft friable condition, easily re- -material is finished by the usual grinding and bolting operations. Ordinary unbolted duced to powder.

The product which I wish to claim as novel is the intermediate product produced by precipitation, v the manner described above and before the antimony pentasulphide' contains a consider- ...able quantity of'hard gritty particles and is so, gelatinous asto be-washed with difliculty, whereas the product-produced accord-V ingito my p resent inventlon is, as stated uaboi'e, softand friable and easily washed and;.pulv erized. I

This difference in milling qualities'is parimportant since the product is mamly used as a, pigment and the color of antimony pentasulphide is greatly impaired iffthelmaterialis subjectedto very much on pounding, whichdecomposes the sul do to some extent and causes the materi to be filled with black particles.

- Variations-in this process may be made instead of sodium sulphantimo- 1 mony pentasulphide, is not limited to this use and is of general ap lication within the scope of the appendedvc aims. I have prepared aluminum hydroxide in a non-gelatinous condition by addi'ni grystals of potash alum to ammomum h xide sulphides of tin and arsenic have also been prepare according-to my droxide may. also be precipitated .m non gelatinous form by the use of this princlpl. I find that in carrying out my process an excess of acid has a beneficial effect. In the is about double example given above, 125 grams of sulphuric rindingthe ordinary pre- When my precipitate filtering and washing'in 4 =phide-are precipitated byboth; of these re-".

lzgb calciumsulphantimonate, Ca, 1

- lnat'e, case hydrochloric acid is preferablyfemployed as the precipitant instead of sulphuric acid. f ,7

' As stated above, my process, while of spa-- icial" advantage in the preparation of antiprocess by adding crystals 'of' sulpharseuates and sulphostannates to suitable acids, giving fine precipitates that.

easily washed and ground. Ferric hy-.

greate r or less excess of acid maybe used r and I hayofeund um grams of acid the same example will also give satisfactory results, though the product contains rather more of the undesirable gritty'particles than when a larger excess of acid is employed.

The precipitation of antimony pentasultimonate and sulphuric-acid,takes-place in' one of two ways, either according to'fthe equationgiven above, where 6 molecules of sul huric acid' react with 2 molecules of sodium sulphantimonate, or. according to: other reaction where 3 molecules of sul huric acid will react with 2 molecules of s dium bisulphate, as in 'the above equation.

- sulphantimonate, and where sodium phate is apparently produced instead of s0= Identical quantities of antimony pentasul-.

actions, and where anexcess of acid is're ferred to herein, the means more ac d than tasulphide by the reaction last mentioned,

is required for precipitating antimony {pensulphide, although this 125 gramsgo is the chemical equivalent of 200- grams ,'df

I claim as my invention:

1. The process that comprises treating a sodium sulphantimonate according to they} reaction where 6 molecules of acid. react with 1 2' molecules of sodium sulphantimonate;

solid water-solublesulphosalt with an acid precipitating a sul hide therefrom.

. rocess t at comprises-introduc-v ing crysta s of a water-soluble sulphosalt into i an acid capable of decomposing the said salt and recipitating a sulphide therefrom,

3. he process that comprises treating a solid water-solublesulphosalt with an acid capable of decomposing the said salt and antimony pentasulphide therefrom.

5. The process of preparing antimony pentasulphlde that comprises treating with sulphuric acid a solid sulphantimonate ca.- pable of reacting with sulphuric acid to precipitate antimony pentasulphide.

6. The

acid. 7 7. The recess of preparing antimony pentasulphide that comprlses treating solid recess of preparing antimonyenta'sulphide that comprises treating solid sodium sulphantimonate with a? mineral sodium sulphantimonate with sulphuric 8 The process of preparing antimony a capable of decomposing the said saltand 1 d of decomposing-said salt and precipitating 116 t phidetliat comprises introducing #53116 :crystal-line'T'sodium sulphantimonate 'lute sulphuric acid.

filteringfwaslii'ri and drying the resulting r recipltate p t I g 1' jbf"preparing antimony ntasulpludeirgthht comprises introducing Olidllfsodium sulphantimonate intoi'idilutei'siilpliuric acid, and filtering,

-Washiiigand g the resulting precipif preparing antimony file process comprlses' diluting about pentasulphide that:

125 t parts :by weig new i wmaiz ?Bet-m e!,

I "the. process of -preparing antimony treating a solid ht, ,of concentratedsulf lutedp'acid witli-about 2 00 parts'bji weight of crystalline sodium sulphantimonate, al-

lowing the material to reactfwith agitation, until the evolution of gas ceases, and filtering, washing and drying the resulting pre cipitate.

13. ground antimonypentasulplii de in soft fri able form, and capable of being readily washed, dried and ground to fine powder.

14. As a new article of manufacture, unround antimony pentas'ulphide irecipitat ed in the form of soft, friable agg omera'tes.

15. a new article of manufacture, unground antimony pentasulphide precipitatil washed, dried and ground.

testimony whereof, Wilson, liave hereunto set lny hand.

NORMAN R WILSON; witnessesz C.- P; LnAcH, f-

.H. L.W1rlL1Ja1mso1- z Asanew article of manufacture, un-

ed in the form of soft. masses which are read-.

I- thesaid Norman I 

